A requirement is basically a rule or instruction that needs to be followed in order to achieve a certain goal. For example, if you want to build a car, there are certain requirements you need to meet in order to make sure the car is safe and functional. These requirements might include things like having enough materials to build the car, following certain engineering standards to make sure the car won't fall apart, and making sure that the car has all the necessary features that people expect in a car (like seats, a steering wheel, and brakes).
Requirements can be very specific or very general, and they often depend on the context and the goal you are trying to achieve. For example, if you are building a computer program, the requirements might involve making sure the program can do certain things (like save and retrieve data), work on certain types of computers, or fit into a certain budget.
One thing to keep in mind with requirements is that they often have to be prioritized, because it's not always possible to meet every requirement perfectly. Sometimes you have to make tradeoffs, either by making compromises (like building a car with fewer features to meet a lower budget) or by deciding that some requirements are more important than others (like prioritizing safety over appearance when building a car).